Means for controlling electric circuits



June 27, 1939.

Original Filed Jan. 50, 1935 K. E. SCHIMKUS ET AL MEANS FOR CONTROLLINGELECTRIC CIRCUITS 14 AM T 1 -29 22 23 24 12 25 25 10 g9 E7 141 IPatented June 27, 1939 UNITED STATES MEANS FOR. CONTROLLING ELECTRICCIRCUITS Kurt E. Schimkus,

Detroit, Mich., and Willy Dumke, Chicago, Ill., assignors, by mesneassignments, to Hannah 0.

Mich.

Chereton, Detroit,

Application January 30, 1935, Serial No. 4,056 Renewed November 4, 193810 Claims. (Cl. 200-113) The invention relates to devices for increasingand decreasing the flow of current in electric circuits and has as itsgeneral aim the provision of a novel means which is simple,substantially free of mechanical noise, practically indestructible fromoperative causes, and has no moving parts requiring original orsubsequent adjustment.

An object of the invention is to provide a novel device of the aboveclass which is capable of producing regular pulsations of current andoperates with low current loss and high efliciency.

Another object is to provide a device of this character which embodiesnovel means for effecting intermittent current pulsations through therecurrent conversion of a current conducting substance from one physicalstate in which it oflers relatively little resistance to current flowinto another physical state in which current flow is substantiallyprevented and thereafter reconverting all or part of the substance toits original state.

A further object is to provide such a device which embodies means foreffecting cycles of current pulsations including a conductive materialcapable of changing its physical state in response to the application ofrelatively little heat energy arranged to be interposed in the circuitand confined in part to produce a predetermined resistance to currentflow, whereby to generate heat energy ample to cause a change in thephysical state of said material at some point in the confined partthereof resulting in a break of the circuit, the circuit being partiallyor entirely reestablished immediately thereafter by the return of all orpart of said material to its original physical state.

More specifically stated, an object of the invention resides in theprovision of a device arranged to be connected in a circuit andincluding, as a current conducting medium, mercury or mercury amalgam ina container which embodies a constriction, in the nature of a capillarytube, of such predetermined dimensions as will, when the device iscarrying the electrical energy for which it is intended, produce thatdegree of heat required to volatilize a small portion of the mercury inthe constriction, whereupon the gaseous mercury interrupts thecontinuity of the metallic mercury and not only breaks the circuit butentirely stops or minimizes heat generation to permit condensation ofall or part of the mercury vapor and partial or entire reestablishmentof the circuit.

In conjunction with the foregoing, another object is to provide a noveldevice embodying means which provides for the expansion and contractionof the mercury or other conducting medium under temperature changes,both internal and external, which means in dimensions is correlated withthose of the restricted tube to insure proper operation.

Another object is to provide a device of this character which is notaffected by external shocks or vibrations and may be used in anyposition.

A further object is to provide a novel device in which failure of thedevice due to the introduction of extraneous matter, such as an air or15 gas bubble in the constricted portion of the conducting medium, isnot possible.

Stated more specifically, another object is to provide a deviceembodying a mercury container having a restricted tube opening into asub- '0 stantially central point of the container, the quantity ofmercury in the container being less than the amount required to fill itand more than that required to cover the end of the tube in allpositions of the device and at the lowest temperature to which thedevice may be subjected.

Other objects and advantages will become apparent in the followingdescription and from the accompanying drawing.

Application, Serial No. 179,893, filed'December so 15, 1937, in the nameof Kurt E. Schimkus as a continuation hereof contains claims to thegeneric operating characteristics of the present invention and to thoseother novel features thereof which are not claimed herein. 3

In the drawing:

Figure 1 is a sectional view of a device embodying the features of theinvention.

Fig. 2 is a similar view of such a device modifled in form for full-waveoperation.

Figs. 3 and 4 are wiring diagrams of circuits showing respectively themanner in which the devices illustrated in Figs. 1 and 2 may beconnected.

While the invention is susceptible of various 45 modifications andalternative constructions, we have shown in the drawing and will hereindescribe in detail the preferred embodiment, but it is to be understoodthat we do not thereby intend to limit the invention to the specificform 50 disclosed, but intend to cover all modifications and alternativeconstructions falling within the spirit and scope of the invention asexpressed in the appended claims.

Briefly stated, the features of the present inu vention are attained byutilizing the property of certain current conducting substances, ofwhich metallic mercury is an excellent example, to change the physicalcondition or state thereof, when subjected to heat, temporarily toanother physical state in which the substance is either non-conductiveor offers such high resistance to current flow as to be substantiallynon-conductive. With such a substance, and knowing in advance theaverage current values to be normally encountered by the device, thesubstance may be arranged to impart a substantially fixed resistance tocurrent flow of such value that the heat energy derived thereby willcause the conversion of a minute but suflicient quantity of saidsubstance to its non-conductive condition to break the circuit andeither entirely interrupt or decidedly decrease the current flow.Following the break the production of heat energy entirely or in largepart ceases and the substance which has changed its physical statereverts entirely or in substantial part to its original state andreestablishes the circuit. This constitutes one complete operatingcycle. In operation the cyclic frequency may be exceedingly high and isentirely independent of mechanical or like limitations. Preferably thepredetermined fixed resistance is obtained by forming the substance toprovide a current path which is of predetermined dimensions.

The device thus functions to translate the direct current output of asource of electrical supply into a pulsating current, in which theactual current values vary at a predetermined frequency between maximumand minimum values. In certain instances, and depending upon theselection of the material which undergoes the change of state and alsodepending upon the electrical characteristics of the associated circuit,the current flow may be entirely interrupted at the conclusion of eachheating phase, and all of the converted material may revert to itsoriginal state during the cooling phase. In other instances, the heatingphase may produce only a partial interruption of the current fiow andthe cooling phase may result in only a partial reconversion of thematerial. In'either event, however, the changes of state are accompaniedby and result in periodic variations of the current between well definedmaximum and minimum values, and in the illustrated embodiments of theinvention, these variations are abrupt and sharp. Throughout thefollowing description and in the appended claims, accordingly, termssuch as make, break, interrupt, recondense, reestablish, revert,reconversion, increase, decrease and the like are used in a generic andrelative sense. In the claims also, the term normal" current is utilizedto refer to the increased value of current which flows through thesubstance at the conclusion of each cooling phase, or at the conclusionof each partial or entire reconversion of the substance to its originalstate, which normal value of current again initiates the conversion ofthe substance to its relatively non-conducting state.

Referring more particularly to the illustrative forms of structure shownin the drawing, what may be termed a pulsator interrupter is shown inFig. 1. Hereinafter mercury or mercury amalgam will be considered asexemplary of a suitable substance, the changes in the physical statesthereof being from a normal fluid state to a gaseous state, followed bycondensation to the fluid state. In the description and in the claims.the term mercury is used in a sense generic to both mercury and mercuryamalgam. The device shown in Fig. 1 comprises two mercury containers I!)which may be of any suitable size and shape but are preferably in theform of hollow substantially spherical members. These containers arespaced apart and are connected by a tubular member ll having a bore l2oppositely communicating with the interior of each container. Where thedevice is intended to handle electrical currents of relatively lowvalue, the containers and the tube may well be fashioned of glass, suchas that known commercially as Pyrex. For higher values a strongermaterial,may be necessary.

The bore is filled with mercury and the containers are nearly filled asshown, the mercury body being indicated at l3. Connection of the devicein an electric circuit so that the mercury in the bore I2 is included inthe circuit and may be established by a terminal l4 sealed, as at l5, ineach container wall and contacting the body of mercury in eachcontainer.

Since in the transmission of electrical energy resistance is inverselyproportional to the size of the conductor, the fixed resistance of themercury may be advantageously predetermined and permanently maintainedby properly dimensioning the bore l2. For currents of low potential,such as those drawn from a storage battery, I

the bore is quite restricted and the tubular members may be in thenature of a capillary tube wherein the bore diameter is a fraction of amillimeter.

Moreover the length of the bore must be properly calculated apparentlybecause of the fact that the mercury vapor produced whenthe change ofphysical state occurs has substantially greater volume than the fluidmercury. In capillary tubes or like small diametered bores, theresistance to fluid flow therethrough is relatively great. Hence, if thebore is excessively long the gaseous mercury cannot readily overcome theflow resistance offered with the result that the circuit may not bebroken or is not broken sharply and regularly. Conversely, if the boreis too short, expansion of the created gas may cause a greaterseparation of the mercury column than is necessary to break the circuit.In this case a permanent break in the circuit may result by failure ofthe broken ends of the column to reunite or an undesirable delay inclosing the circuit occurs due to the lag in the flow of the materialcaused by the resistance to flow. It is, therefore, desirable topredetermine the length of the bore to obtain that intermediate lengthwherein the circuit is broken sharply, regularly and in which therelationships are so balanced that substantially the initial conversionof mercury from the fluid to the gaseous state will "break the circuit,immediately followed by a reconversion of gas to fluid which closes thebroken circuit. When the relationships are of this nature the device isexceeedingly sensitive, will start at once upon closing the circuit andwill operate at a relatively high frequency.

Since the break of the mercury column is the result of change in thephysical state of mercury caused by the flow of electrical energy, theaverage values of the electrical current which is to be interrupted bythe device will determine the dimensions of the bore. Generally statedthe dimensions will increase as the values of the electrical currentincrease. As a particular example of "dimensions which have been foundsatisfactory in a device for producing pulsating current from a storagebattery in a circuit adapted to energize the primary winding of atransformer, the restricted tube may have an approximate diameter oftwenty-two one-hundredths of a millimeter and a length of approximatelythree and eight-tenths centimeters.

Another factor to be considered is the quantity of mercury in thecontainers i0 since an opposing force is thereby imposed upon each endof the mercury column in the bore, which force will also affect thesensitivity of the device in operation. Consequently the quantity offluid in the containers will, if not held within predetermined maximumand minimum limits, have substantally the same efiect as a bore i2 whichis too long or too short. The quantity of fluid, in general, increasesas the dimensions of the bore l2 increase. In the present instance themercury in the containers l0 nearly but not quite fills the containers,the bubbles of air or other gas It in each container being particularlyprovided to allow for the expansion and contraction of the mercury astemperature variations occur not only externally but internally as thedevice passes between inoperative and operative conditions. Suchexpansion introduces another factor to be considered since the pressureof the gas in the bubbles i6 increases as the mercury expands and thusimposes additional force on the mercury column in the bore which actsthereon in the same manner as does the quantity of the mercury.

However, once the several factors to be taken into consideration areknown it is not difficult to determine the dimensional relationships ofthe several parts in the fluid confining system of a device intended foroperation in connection with current of a known average value. In thespecific illustration of container dimensions, a sphere of approximatelyone and nine-tenths centimeters has been found suitable in connectionwith a restricted tube of the dimensions above mentioned.

Unless, in a device of this character, some means is provided forpreventing the entrance of a bubble of extraneous gas, such as air, fromthe bubbles iii, the device can be used satisfactorily only in asubstantially horizontal position, due to the permanent interruption ofthe mercury column by the entrance of such a bubble. To this end thepresent invention embodies means whereby no foreign matter of any kindcan enter and become lodged in the bore I2. Thus, as shown, each end ofthe tubular member ii is extended through the wall of the associatedcontainer ID to a point which is substantially centrally thereof so thatthe ends of the bore are located approximately on the center points ofthe containers. The ends of the tubular member ii are preferablyrounded, as indicated at IT, to avoid trapping air bubbles on the endsas the mercury is introduced into the containers through the fillingopenings, shown in sealed condition at l8. With this arrangement ofparts, and with the containers properly dimensioned, the quantity ofmercury in the containers will be more than ample to cover the exposedends of the bore i2 regardless of the position of the device. Hence, airbubbles, or indeed any foreign matter, such as minute particles of oxideof mercury, cannot possibly enter the bore.

It has been found that the union between the tubular member and eachcontainer is stronger and the mercury is better supported if the wallportions of the containers about the tubular member are turned inwardly,as shown, to form a smooth junction. Moreover, to lessen electricalresistance externally of the bore i2 the I terminals H are extended topoints immediately adjacent to the bore ends.

The device shown in Fig.1 is intended primarily to be used forcontrolling the simplest type of circuit, such as a circuit foreffecting energization of a transformer by a pulsating current. In Fig.2 a device is shown for controlling a circuit which includes twobranches, such as a circuit by which energization of a transformer bycurrent alternating in direction is eflected. The construction of thelatter device, as well as the correlation and relationship of the partsthereof, is substantially the same as that shown in Fig. 1, as isindicated by the use of the same reference numerals. However, in thisform, the tubular member i I is interrupted between its ends and theinterrupted ends communicate with opposite sides of an intermediatecontact chamber ll. The casing forming this chamber is preferablysmaller than the containers in and is filled with El mercury. At oneside a terminal 20 extends through the casing wall to a pointintermediate the opposed ends of the interrupted bore i2. In this devicethe operation is the same as in the first device except that tworestricted bores are as provided for controlling the branch circuits.Since it is practically impossible to balance the bore branches exactly,the initial breaking of the circuit will occur in one or the other ofthe bores, after which the circuit through the other I bore will bebroken while the first circuit is being reestablished. Consequently thisform of device will be effective to make and break" branch circuits inalternation.

In illustration of circuits embodying these dea vices and in descriptionof an environment in which these devices have been found particularlysuitable, Figs. 3 and 4 show circuits employed in converting low voltagedirect current from a storage battery into high voltage direct currentfor (l supplying the B circuit of a radio receiving set with currenthaving a proper potential. Such circuits are used largely in theso-called 8" battery eliminator devices employed in motor vehicleinstallations of radio receiving sets.

Fig. 3 shows the device in the capacity of a pulsator. Thus, oneterminal i4 is connected through lead 2! with one side of a storagebattery 22 which in turn is connected by lead 23 and interposed controlswitch 24 with one end of the primary winding 25 of a step-uptransformer 2G. The other end of the primary winding is connected bylead 21 with the other terminal II. This circuit is effective toenergize the primary winding intermittently and always in the samedirection, which pulsating current is however reflected as analternating current in the transformer secondary winding. A condenser 28is connected across the device by leads 2! to the leads 2| and 21 andserves to tune the circuit and reduce the slight electrical noiseresulting from the operation of the device. The condenser 28 alsoappears to affect or control the frequency of the device.

To complete the circuit any suitable means for rectifying the currentfrom the secondary winding 30 may be employed, such as a thermionicvalve 32. Herein one end of the secondary winding'is connected by lead3i with the plate element 33 of. such a valve, while the cathode ele- 7|ment 34 is connected with an output lead 35 to one side of a suitablefilter system, generally designated 36. The other end of the secondarywinding is connected by lead 31 with the other side of said system. Acondenser 38 may be connected by leads 38 across the leads 3| and 31from the secondary winding. The valve has a heating filament 39connected by leads 39 directly with the battery 22, although the switch24 is interposed.

In operation, closing of the switch 24 produces a current flow throughthe interrupting device, the resistance to which flow almost instantlyheats the mercury in the bore and causes a small 5 part of the mercuryto volatilize. This change of state through the increased volumeoccupied by the gas breaks the circuit and immediately thereaftercondensation of the gas reestablishes" the circuit. Repetition of thiscycle of operation at a high frequency is effective to energize theprimary winding intermittently and produce an alternating current ofhigh voltage in the secondary winding which is rectified to anintermittent direct current by the valve 32, and smoothed into 5 asubstantially even direct current by the filter system for delivery tothe proper terminals of a radio receiving set.

With the circuit shown in Fig. 4 energy from a storage battery istranslated into pulsating components successively opposite in direction.Thus, the end terminals l4 from the device are connected through leads40 with the ends of primary winding 4|, condensers 42 of proper valuebeing connected in series across the leads 40 by 35 leads 43. Theintermediate or third terminal 20 of the device is connected by lead 44with the lead 43 between condensers 42 and with a control switch 45which, in turn, is connected with one side of the battery 46, the otherside of which is connected with an intermediate or center tap" 4'! fromthe primary winding. Each end of the secondary winding 48 is, in thissystem, connected through a lead 49 with a plate element 50 of athermionic valve 5| of the full-wave type. 45 A cathode element 52cooperatively related to said plate elements is connected with an outputlead 53 to a suitable filter system which may be of the type shown inFig. 3 and is generally represented by the first condenser. A heatingfilament 54 is connected independently with the battery through leads 55and a condenser 56 is connected across the secondary winding by leads51.

The operation of this system is substantially 55 the same as that of thecircuit illustrated in Fig. 3. However, in this system the alternatemaking and breaking of the circuits in the opposite branches of the boreis effective to energize first one and then the other section of the 60primary winding, the current flow being in opposite directions. Properadjustment of the values of the condensers 42 may be employed tosynchronize the current pulsations in the two branches of the bores. Theresulting alternating current in- 5 duced in the secondary winding isrectified, filtered and substantially direct current of high potentialis delivered to the receiving set. This system is probably moreeiiicient than the first described system,

From the foregoing it will be evident that a novel circuit controllingmeans has been provided which is unusually simple in construction. Thedevice occupies a closed container. Hence the substance therein is notsubject to oxidation or v 15 other chemical changes and will remain inits original condition indefinitely. The device is emcient since theonly current loss is the result of the relatively low resistance offeredby the substance imposed in the circuit. The only change caused by thecurrent flow is one of physical state and the substance, therefore, isnot expended or in any manner affected deleteriously by operation. Thereare no moving parts in the present device, hence accurate adjustment isnot required. Upon determination of the proper correlation of dimensionsand quantity of substance for a current of average values quantityproduction of uniform devices may be easily obtained. In addition, thedevice may be used in any position and under practically all operatingconditions without injury thereto or impaired performance. As a resultof these several advantageous features devices embodying the presentinvention are exceedingly practical, eflicient, adaptable for many usesand may be economically manufactured.

We claim as our invention:

1. A circuit controlling device comprising in combination a containerhaving a restricted bore opening into the body of the container, acontact terminal having a portion exposed within the body of thecontainer, the container being completely filled by a quantity ofmercury and by a free gas bubble, so as to allow for expansion andcontraction of the mercury, the quantity of the mercury being sufiicientto cover the end of the bore and engage the terminal in any posi tion ofthe device.

2. A circuit controlling device comprising in combination a containerhaving a restricted bore opening into the body of the container, acontact terminal having a portion projecting into the container to apoint adjacent the end of the bore, the container being completelyfilled by a quantity of mercury and by a free gas bubble, so as to allowfor expansion and contraction of the mercury, the quantity of themercury being sufficient to cover the end of the bore and engage theterminal in any position of the device.

3. A circuit controlling device of the character described comprising,in combination, a casing having a passageway therein of restricted sizeand a hollow chamber communicating therewith, said passageway beingfilled and said chamber partially filled with mercury, the end of saidpassageway being spaced inwardly from the wall of said chamber so as toprevent the entrance of bubbles from said chamber into said passagewayin all positions of the casing, and means for establishing an electricalcircuit through the mercury in said casing.

4. A circuit controlling device comprising, in combination, spacedcontainers, means connecting said containers having a passage therein ofrestricted size communicating with the interior of said containers nearthe centers thereof, mercury in said passage and containers in suchquantity as will fill the passage and cover the ends thereof in anyposition of the device, and means establishing electrical contact withthe mercury in each container.

5. A circuit controlling device of the character described comprising,in combination, a casing having a passageway therein of restricted sizeand a hollow chamber communicating therewith, said passageway beingfilled and said chamber partially filled with mercury, the remainder ofsaid chamber being occupied by a free gas bubble, the junction of saidpassageway and said chamber being located to prevent the entrance ofsaid bubble from said chamber into said passageway in all positions orthe casing, and means for establishing an electrical circuit throughsaid mercury.

6. A circuit controlling device comprising, in combination, a containerfilled in partwith mercury and in part with a gas bubble, a mercuryfilled tube of restricted dimensions connected with the container toprovide a continuous mercury body, means for preventing interruption ofthe continuity of said mercury body by movement of said bubble into aposition adjacent the mouth of said tube, and means for passing currentthrough the mercury in said tube.

7. A circuit controlling device comprising, in combination, a containerfilled with mercury and a freely movable gas bubble, a mercury filledtube of restricted internal dimensions connected with the container toprovide a continuous mercury body, and means for passing current throughthe mercury body, said container and tube having a point where themercury in one joins the mercury in the other inaccessibly located withrespect to the movable bubble whereby in no position of the device canthe bubble interrupt the flow of current.

8. A circuit controlling device comprising, in combination, a pair ofcontainers each filled in part with mercury and in part with a freelymovable gas bubble, a mercury filled tube of restricted internaldimensions extending between said containers to provide a continuousmercury body, electrical connections for passing current from onecontainer to the other through the mercury in said tube, and means forpreventing movement of the gas bubble in either container into aposition in which said bubble may interrupt the current flow between themercury in a container and the tube.

9. A circuit controlling device of the character described comprising,in combination, a casing having a passageway therein of restricted sizeand a hollow chamber communicating therewith, said passageway beingfilled and said chamber partially filled with electrically conductingliquid material, the remainder of said chamber being occupied by a freegas bubble, the junction of said passageway and said chamber beinglocated to prevent the entrance of said bubble from said chamber intosaid passageway in all positions of the casing, and means forestablishing an electrical circuit through said material.

10. A circuit controlling device of the character described comprising,in combination, a casing having a passageway therein of restricted sizeand a hollow chamber communicating therewith, said passageway beingfilled and said cham ber partially filled with electrically conductingliquid material having the property of changing upon being heated to arelatively non-conducting state, the remainder of said chamber beingoccupied by a free gas bubble, the junction of said passageway and saidchamber being located to prevent the entrance of said bubble from saidchamber into said passageway in all positions of the casing, and meansfor passing an electric current through said material so as to eflectsaid change of state of at least a part of said material in saidpassageway.

KURT E. SCHIMKUS. WILLY DUMKE.

